Finding out how many reps you need to do to get the results you want is a must learn. If you are looking to become a bodybuilder and build big muscles, then you will be looking to do higher amounts of weights and fewer repetitions. If you are looking to develop a slimmer body type with a slimmer figure than you want to work with lower weights and higher reps.
The following are suggestions for repeats for different types of results.
High weights: this category involves a large amount of weight. You want to make sure you can perform at least 6 to 12 repetitions of this weight. Remember that higher weight leads to a higher chance of injury. Only lift heavier weights if you have previous experience with weightlifting or your training for an athletic event.
Moderate weights: In this category, you will be looking to do at least 12 reps for your given weight. This weight class is much less prone to injury risk and provides you with a good balance between getting stronger and building muscular endurance.
Low weights: If you are an older adult, you want to avoid any possibility of injury, so you should use the lightest weight that allows you to do at least 10 to 15 repetitions. If you are in this category you can even do a much lower weight.
Keep in mind that the results of these exercises are highly dependent on your genetic makeup. Some of us have body types that will allow us to look like Arnold with just a little exercise. Others have body types where no matter how much they train, they will always look lean. Adjust your training to your body type.
If you are looking to increase your endurance, you need to make sure you do at least 12 reps. If you want to build bigger muscles, you should make sure to do 6-12 reps while increasing the number of sets to 3-6. You want fewer reps and more weight. No matter what level you choose, remember to always lift with a partner. A lifting partner will greatly reduce the risk of injury.